1. Field of the Invention
The invention relates to a membrane, especially a membrane for use in a fuel cell, as well as to a fuel cell containing such a membrane.
2. Background Information
A fuel cell comprises a cathode, an anode and an electrolyte disposed between the anode and cathode. An anode chamber adjoins the anode and a cathode chamber adjoins the cathode.
In a methanol fuel cell, methanol is fed as working gas to the anode chamber. On the cathode side, oxygen or air is supplied as oxidizing agent. By means of a catalyst, hydrogen ions are formed from the methanol at the anode. The hydrogen ions pass through the electrolyte, which typically comprises a membrane, and on the cathode side combine with the oxygen ions formed from the oxidizing agent to produce water. In the process, electrons are liberated and electrical energy is generated.
From German Patent 196 46 487 C2 it follows that the electrolytes of known fuel cells allow not only the hydrogen ions (protons) to pass, water in the form of hydrate shells around the protons and even some of the fuel (CH3OH) can also pass. This means on the one hand that too much water is transported from the anode to the cathode, thus adversely affecting the thermal balance, while on the other hand methanol is also additionally transported, thus leading in general to development of a mixed potential at the cathode and thus to a perceptible loss of efficiency.